基于粮食生命周期碳核算的粮食安全影响研究进展

基于粮食生命周期的碳核算可找出碳排放较高的活动，有利于碳中和目标下的粮食安全.本文综述了粮食种植阶段及副产物资源化利用阶段的粮食全生命周期碳核算研究进展，并提出了不同阶段的碳减排措施.稻田CH₄与旱地N₂O是种植阶段直接碳排放的主要来源，间接碳排放主要来自氮肥施用，土地利用变化是影响种植阶段粮食安全的另一因素.未来应提高氮肥利用率，合理规划城市建设，建立粮食-林地协同发展的碳核算系统，发展非粮燃料乙醇.能源政策下乙醇副产物生产饲料可降低饲料行业对粮食的需求，粪便还田可减少工业化肥使用，提高土壤质量.未来应继续从碳足迹角度探究乙醇副产物资源化利用对粮食安全的影响，开展作物不同生长期的碳核算研究，帮助建立粮食全生命周期内更细化时间尺度上低碳高产的粮食安全模式，保障粮食安全稳定格局. 

Food security impact gauged by carbon accounting of food life cycle

Food security is closely related to society and national economy. Carbon accounting based on food life cycle could identify activities with high carbon emissions, conducive to ensuring food security under the goal of carbon neutrality. The life cycle of grain under the change of energy policy includes farmland planting, ethanol preparation and ethanol by-product resource utilization, and manure-return to the field. CH₄ emission is the main source of direct carbon emission, and indirect carbon emission is mainly due to application of chemical fertilizer, especially nitrogen fertilizer. Land use change (due to urban expansion, conversion of farmland to forests and changes in energy policies) is another factor affecting food security. Future nitrogen use efficiency should be improved, organic fertilizer should be applied, urban construction should be rationally planned, carbon accounting system should be established for coordinated development of grain and forest land, and non-grain fuel ethanol should be developed. Impact of resource utilization of food crop by-products on food security was analyzed, food by-product production of feed was found to reduce feed industry demand for food, manure-return to the -field could reduce the use of industrial fertilizers and improve soil quality. Impact of by-product feed production and manure-return on carbon emissions were not studied．In the future, carbon accounting could be combined with food life cycle to help policy makers to find a low-carbon and high-yield food security model in the life cycle to ensure a stable pattern of food security.